Symmetrical flue boiler with central firebox and offset magazine



w. Fi. SM'ITH Apnl l, 1952 SYMMETRICAL FLUE BOILER WITH CENTRAL 2,591,627

FIREBOX AND OFFSET MAGAZINE P Filed on. 29. 154 s Sheets-Sheet 1 Attorney April I, 1952 w. H. SMITH Y 2,591,627-

. SYMMETRICAL FLUE BOILER WITH CENTRAL FIREBOX AND OFFSET MAGAZINE Filed Oct. 29, 1948 3 Sheets-Sheet 2 I Attorney A ril l 1 52 w. H. SMITH p 9 SYMMETRICAL FLUE BOILER WITH CENTRAL 2591'627 FIREBOX AND OFFSET MAGAZINE Filed 001;. 29, 1948 3 Sheets-Sheet 15 A itorney Patented Apr. 1, 1952 SYMMETRICAL F LUE BOILER WITH CEN- TRAL FIREBOX AND OFFSET MAGAZINE William Herbert Smith, East Molesey, England Application October 29, 1948, Serial No. 57,250 In Great Britain November 3, 1947 6 Claims. (01. 122-130) This invention relates to boiler furnaces; more particularly for central heating by hot water or steam, of the kind provided with a fuel compartment which feeds fuel to a combustion zone at the bottom of the furnace through which primary air is forced, the hot gases from this combustion zone passing through internal flues in the boiler.

From. one aspect the invention provides a boiler furnace of the kind referred to in which internal fiues pass from the combustion zone to the top of the boiler and then downwardly towards the bottom, the section of the downwardly extending parts of the flue becoming more elongated below a fuel hopper at the rear of the boiler so as to allow of correct area being provided throughout for the flue gases While allowing the fuel hopper to be the full width of the boiler and the firebox to be of maximum width. For example the downwardly extending flues may be of rectangular section with their longer dimension running from front to back of the boiler and this longer dimension increases below the level of the fuel compartment and the smaller dimension decreases gradually from top to bottom.

The primary air is delivered through a tuyeresituated within-the fuel in the firebox and directed downwardly.

From another aspect, the invention provides a boiler of the kind referred to in which primary air is delivered by a blower under the control of a thermostat operating in accordance with the temperature of the water. The thermostat may act to switch off an electric motor driving the blower when the water temperature rises above a pre-determined value and to switch it on when the water temperature has fallen to another predetermined value.

Other parts of the invention are embodied in the preferred form of boiler which will now be described-in some detail by way of example with reference to the accompanying drawings in which:

Fig.1 is a front elevation partly in section of a preferred form of boiler,

Fig. 2 is a section on the line IIII of Fig. 1, and

Fig. 3 is a plan view, partly in section on the .l1ne'I1I--III of Fig. 1.

In this form, the boiler l is substantially rectangular in plan and the fuel hopper 2 extends across the full width at the back. The fire box 3 is immediately below the fuel hopper.

A heat chamber 4' extends vertically from the fire box 3 and from this chamber fiues 5 pass downwardly at each side to the bottom 6 of the chamber 4 is divided by a central partition I4 depending from the top of the boiler, and this partition is also hollow and in communication with the rest of the water spaces. The partition I I4 thus forms an economiser. It will be seen that the water in the boiler is in effect distributed through a large number of relatively narrow passages so that there is a very large surface in contact with the heating gases which promotes efficiency in heating.

The side walls 8 of the heat chamber 4 slope inwardly from the bottom to the top and as these walls are of uniform thickness, this gives (with vertical side walls to the boiler) a gradually decreasing width to the side flues 5. To preserve the proper cross-sectional area for the flue gases, the dimension of the flues 5 from back to front of the boiler increases from about the level of the bottom of the fuel hopper 2 to the boiler bottom 6 as shown in dotted lines in Figs. 2 and 3. This arrangement enables the fuel hopper to be of the full width of the boiler while the fire box at the bottom of the boiler is of maximum width.

The fire box 3 is supplied with fuel from the hopper 2 through a throat I5 designed to give correct formation to the fuel. The throat is flared and deflectors l 6 are also provided to guide 7 the fuel into the fire box so as to give a correct formation to the fuel therein. The orifice leadingv from the coal hopper is at such a height and is so shaped that it causes the coal falling by gravity to fall sufiiciently forward adequately to cover the nose of the tuyre, but is restricted sideways front of the apparatus provides access to the flre box 3 and a sight glass 20 is provided in this door.

Air is supplied to the fire through a waterjacketed tuyere 2| arranged below the normal fuel level (indicated at 22) and directed downwardly so that the air passes first downwardly and then upwardly through the fuel to the heat 3 chamber. The water-jacketed tuyere 2i acts as a hot-spot? in the fire.

The tuyere 2| projects into the fire box from the back wall It] and is normally completely covered by the fuel.

The water in the jacket 23 of the tuyere connects with the water in the rest of the boiler and the top of the jacket is sloped to assist the natural convection of the water and to guide the fuel into correct position.

Air is forced through the tuyere 21 by a blower 24 situated at the rear of the fire box and driven by an electric motor or other prime mover 25. A circulating pump (not shown) by which the water in the system is circulated, may be mounted on the same shaft as the blower.

Secondary air to ensure complete combustion is led from the blower 24 through hoses 38 to secondary air inlets 3| which open into the heat chamber 3 above the normal level of the fuel.

The water inlet to the boiler may be through the circulating pump. Two water outlets 27 where this is used but as shown is at 26, one at each side are provided at the top of the boiler for alternative connections or for use with domestic supply and central heating respectively.

A thermostat 28 operated by the temperature of the outlet water controls the motor driving the blower 24 by means of a conventional control circuit 28' which is diagrammatically shown in Fig. 3. It is arranged to switch the motor off and stop the blower when the temperature reaches a predetermined value and to switch the motor on, starting the blower, when the temperature has fallen below a lower predetermined value.

During idling periods (when the motor is not running) air for combustion is supplied to the tuyere under the influence of the normal chimney draught through an idling valve 32 in the blower casing. This valve is closed automatically when the blower is in operation by the pressure of the air and opens under gravity when the blower stops.

Cleaning throats 33 for the side fiues are provided in the top of the boiler and a base cleaning throat 34 is provided to the flue below the fire box.

The boiler is enclosed in a casing 35 with asbestos or other insulation between the casing and the boiler shell. There is a cover 3? to this casing which may be raised to allow access to the cleaning throat 33 and the safety valve 33. The lid 39 of the fuel hopper is in this cover.

It will be understood that the invention is not restricted to the details of the specific form described which can be varied without departure from the broad ideas underlying them.

I claim:

1. A boiler comprising a fire-box in the bottom thereof, a fiue having a length substantially coextensive longitudinally with that of the upper part of the boiler and extending upwardly from the fire-box to the top of the boiler and then laterally and downwardly to the bottom thereof, and a fuel hopper at the back of the boiler behind said flue and above said fire-box permitting the fuel hopper to extend the full width of the boiler, said hopper having a fuel discharge port opening into the top of said fire-box, and the downwardly extending portion of said flue being longer from front to back below said fuel hopper than above said fire-box to provide sufficient transverse fiue area and to permit the fire-box to be of maximum width.

2. A boiler according to claim 1 in which the flue is divided by a central vertically disposed hollow partition forming two flues symmetrically arranged in opposite sides of the boiler, the hollow interior of said partition being in communication with the boiler so that the partition forms an economizer.

3. A boiler accordingto claim 2 in which the outer walls of the boiler are substantially vertical, and hollow partitions dividing the upwardly and downwardly extending portions of said flues and being inclined inwardly from the bottom to the top so that the outermost flue portions are of decreasing width from top to bottom enable maximum width of said fire-box, the lower rear edges of said partitions being declined rearwardly toward the bottom so that the outermost flue portions adjacent the fire-box are of increasing length and of substantially uniform cross-sectional area throughout, the hollow interiors of said partitions being in communication with the remainder of the water space in the boiler.

4. A boiler, as defined in claim 1, in which the flue and the bottom of the fire box are defined by hollow walls in communication with said boiler for containing the water to be heated, and a downwardly directed water jacketed tuyere within the fuel zone in the fire box, the water jacket of said tuyere being in communication with the remainder of the water space in the boiler.

5. A boiler, as defined in claim 1, comprising a water jacketed tuyre in said fire box and in coinmunication with said boiler, said hopper discharge tending downwardly from said hopper beside said port to restrict the fiow of fuel sideways and prevent the formation of a heavy fuel bed adjacent the sides or" the boiler.

6. A boiler, according to claim 1, comprising a water jacketed tuyere in said fire-box and in communication with said boiler, a blower and a connection between said blower and said fire box beneath said tuyere by which primary air is delivered under said tuyre by said blower, a ther mostat subject to the temperature of the water in said hollow walls and controlling said blower, a by-pass from said blower into said fire box beyond said tuyre in which secondary air is fed to the fire box above the fuel bed from the blower, and an automatically operating idling valve in the connection of the blower to the fire box and through which air for combustion is supplied when the blower is not in operation.

WILLIAM HERBERT SMITH.

nnransnons oIrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS 

